<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>图片</title>
    <style type="text/css">
        .pic{
            margin: auto;
            position: absolute;
            top: 0;
            left: 0;
            bottom: 0;
            right: 0;
        }
        img {
            max-width: 100%;
            max-height: 100%;
        }
    </style>
</head>
<body>
    <img class="pic" src="/static/images/logo2.png"/>
</body>
</html>